Heat transfer, energy saving and pollution control in UHP electric-arc furnaces

The use of hot-water and evaporative cooling enables the residual energy potential of iron and steel works to be utilized. In particular, water-traversed wall elements are used at present in the top zone of an electric-are furnace. Indeed, the remarkable increase in the electrical power has made the cooling of the wall of the furnace compulsory. Thus, it seems suitable to use the energy recovered in the cooling elements, instead of transferring it to the atmosphere via closed cooling towers. Nucleate boiling leads to a substantially more intensive cooling, but even a limited increase in the input heat flow can be dangerous. If the slag accretions, temperature and thermal power are examined in cases of steady state furnace operation and completely slag-covered arcs, it is found that the thermal losses decrease remarkably as the melting temperature of the slag adhering to the furnace shell increases. The aim of this paper is, first of all, an analysis of heat transfer phenomena in UHP (ultra high power) electric-are furnaces. Then, energy and exergy analyses are dealt with after some remarks about exergy efficiency and chemical exergy of elements. In addition, means to reduce noise, air and water pollution are examined. (C) 2000 Elsevier Science Ltd. All rights reserved.